88 research outputs found
Biomechanics parameters in teenage cyclist – SUV accident and comparison with the pedestrian
The study of the injury caused by the vehicle-teenage cyclist crash is presented in this paper. The
vehicle is a SUV, with high frontal part, in order to compare the results with those obtained previously in the
sedan- teenage cyclist crash and begin a study of the influence of the frontal shape of the vehicle. No variation
is executed on the model of the teenage cyclist and the bike. Three different positions are analyzed: front, rear
and lateral position. The injury on the cyclist head is examined by HIC criterion, in the way indicated in the
rules. Correlation HIC – AIS is used to calculate the lethality of the injuries. The principal conclusion is done
that the injury of the head is more dangerous for the SUV impact than the sedan, but only at the maximum
speed (50 km/h). The injury to the chest is analyzed by 3 ms criterion; the injury is greater for the SUV impact
than the sedan, but the entity is strongly dependent on the cyclist position. A comparison is executed with both
the teenage and adult pedestrian concluding that the pedestrian is subjected to greater injury, because the bike
absorbs a part of the energy in the front and side crash. The more dangerous injury is the telescoping. A further
comparison show that the shape of the bonnet and the height of the frontal part have to be studied in an accurate
way to reduce the injury to pedestrians and cyclists
Sequent depth ratio of B jumps on smooth and rough beds
A hydraulic B-jump has the toe section located on a positively sloping upstream channel and the roller end on a downstream horizontal channel. This paper analyses the B-jump on a rough bed, such as at the transition from a block ramp to the stilling basin. Laboratory measurements of the sequent depth were carried out using three different channel slopes for the rough bed and a single slope for the smooth bed. A solution useful for estimating the sequent depth ratio in a rectangular channel for different relative roughness and bed slope is proposed and positively tested by the present measurements. This solution can also be used to estimate the sequent depth ratio of classical hydraulic jumps or B-jumps on smooth and rough beds
Sequent depth ratio of B-jumps on smooth and rough beds
A hydraulic B-jump has the toe section located on a positively sloping upstream channel and the roller end on a downstream horizontal channel. This paper analyses the B-jump on a rough bed, such as at the transition from a block ramp to the stilling basin. Laboratory measurements of the sequent depth were carried out using three different channel slopes for the rough bed and a single slope for the smooth bed. A solution useful for estimating the sequent depth ratio in a rectangular channel for different relative roughness and bed slope is proposed and positively tested by the present measurements. This solution can also be used to estimate the sequent depth ratio of classical hydraulic jumps or B-jumps on smooth and rough beds
Head Injury Criterion: mini review
Head Injury Criterion (HIC) is the most important parameter
in terms of human survival; it is indicative of brain injuries due to
the impact of the head in numerous cases, with a vehicle. This index
can be estimated by integrating the resulting acceleration of the
head (measured in its gravity center) in a time windo
Imaging of hepatocellular carcinoma recurrence after liver transplantation
Liver transplantation (LT) provides the highest survival benefit to patients with unresectable hepatocellular carcinoma (HCC). The Milan criteria have been developed for the selection of LT candidates with the goal of improving survival and maintaining an acceptable risk of HCC recurrence. Despite this, recurrence of HCC after LT occurs in up to 20% of cases and represents a major concern due to the poor prognosis of these patients. Furthermore, several extended criteria for the selection of LT candidates have been proposed to account for the growing demand for organs and the resultant increase in the risk of HCC recurrence. Radiologists should be aware that HCC can recur after LT with multiple organ involvement. Knowledge of the location and radiologic appearance of recurrent HCC is necessary to ensure the choice of the most appropriate therapy. This paper aims to comprehensively summarize the spectrum of HCC recurrence after LT and to examine and discuss the imaging features of these lesions. CRITICAL RELEVANCE STATEMENT: This paper aims to share a review of imaging findings of HCC recurrence after LT and to make radiologists familiar with the spectrum of this disease
The zCOSMOS 10k-Bright Spectroscopic Sample
We present spectroscopic redshifts of a large sample of galaxies with I_(AB) < 22.5 in the COSMOS field, measured from spectra of 10,644 objects that have been obtained in the first two years of observations in the zCOSMOS-bright redshift survey. These include a statistically complete subset of 10,109 objects. The average accuracy of individual redshifts is 110 km s^(–1), independent of redshift. The reliability of individual redshifts is described by a Confidence Class that has been empirically calibrated through repeat spectroscopic observations of over 600 galaxies. There is very good agreement between spectroscopic and photometric redshifts for the most secure Confidence Classes. For the less secure Confidence Classes, there is a good correspondence between the fraction of objects with a consistent photometric redshift and the spectroscopic repeatability, suggesting that the photometric redshifts can be used to indicate which of the less secure spectroscopic redshifts are likely right and which are probably wrong, and to give an indication of the nature of objects for which we failed to determine a redshift. Using this approach, we can construct a spectroscopic sample that is 99% reliable and which is 88% complete in the sample as a whole, and 95% complete in the redshift range 0.5 < z < 0.8. The luminosity and mass completeness levels of the zCOSMOS-bright sample of galaxies is also discussed
Mass and environment as drivers of galaxy evolution in SDSS and zCOSMOS and the origin of the Schechter function
We explore the inter-relationships between mass, star-formation rate and
environment in the SDSS, zCOSMOS and other surveys. The differential effects of
mass and environment are completely separable to z ~ 1, indicating that two
distinct processes are operating, "mass-quenching" and "environment-quenching".
Environment-quenching, at fixed over-density, evidently does not change with
epoch to z ~ 1, suggesting that it occurs as large-scale structure develops in
the Universe. The observed constancy of the mass-function shape for
star-forming galaxies, demands that the mass-quenching of galaxies around and
above M*, must be proportional to their star-formation rates at all z < 2. We
postulate that this simple mass-quenching law also holds over a much broader
range of stellar mass and epoch. These two simple quenching processes, plus
some additional quenching due to merging, then naturally produce (a) a
quasi-static Schechter mass function for star-forming galaxies with a value of
M* that is set by the proportionality between the star-formation and
mass-quenching rates, (b) a double Schechter function for passive galaxies with
two components: the dominant one is produced by mass-quenching and has exactly
the same M* as the star-forming galaxies but an alpha shallower by +1, while
the other is produced by environment effects and has the same M* and alpha as
the star-forming galaxies, and is larger in high density environments.
Subsequent merging of quenched galaxies modifies these predictions somewhat in
the denser environments, slightly increasing M* and making alpha more negative.
All of these detailed quantitative relationships between the Schechter
parameters are indeed seen in the SDSS, lending strong support to our simple
empirically-based model. The model naturally produces for passive galaxies the
"anti-hierarchical" run of mean ages and alpha-element abundances with mass.Comment: 66 pages, 19 figures, 1 movie, accepted for publication in ApJ. The
movie is also available at
http://www.exp-astro.phys.ethz.ch/zCOSMOS/MF_simulation_d1_d4.mo
The Chandra COSMOS Survey, I: Overview and Point Source Catalog
The Chandra COSMOS Survey (C-COSMOS) is a large, 1.8 Ms, Chandra} program
that has imaged the central 0.5 sq.deg of the COSMOS field (centered at 10h,
+02deg) with an effective exposure of ~160ksec, and an outer 0.4sq.deg. area
with an effective exposure of ~80ksec. The limiting source detection depths are
1.9e-16 erg cm(-2) s(-1) in the Soft (0.5-2 keV) band, 7.3e(-16) erg cm^-2 s^-1
in the Hard (2-10 keV) band, and 5.7e(-16) erg cm(-2) s(-1) in the Full (0.5-10
keV) band. Here we describe the strategy, design and execution of the C-COSMOS
survey, and present the catalog of 1761 point sources detected at a probability
of being spurious of <2e(-5) (1655 in the Full, 1340 in the Soft, and 1017 in
the Hard bands). By using a grid of 36 heavily (~50%) overlapping pointing
positions with the ACIS-I imager, a remarkably uniform (to 12%) exposure across
the inner 0.5 sq.deg field was obtained, leading to a sharply defined lower
flux limit. The widely different PSFs obtained in each exposure at each point
in the field required a novel source detection method, because of the
overlapping tiling strategy, which is described in a companion paper. (Puccetti
et al. Paper II). This method produced reliable sources down to a 7-12 counts,
as verified by the resulting logN-logS curve, with sub-arcsecond positions,
enabling optical and infrared identifications of virtually all sources, as
reported in a second companion paper (Civano et al. Paper III). The full
catalog is described here in detail, and is available on-line.Comment: Revised to omit egregious bold facing and fix missing ',' in author
lis
- …